Little Known ADABAS Features

ADAM Files, Hyperdescriptors, Coupled Files, Multi-client Files

By Dieter W. Storr

Last update: 27 October 2006

In the 80s, when database disc I/Os were costly in both time and money, Software AG (SAG) introduced ADABAS Direct Access Method (ADAM) to save associator (ASSO) I/Os and to get records directly from data storage (DATA) by using SAG’s hash code.

This was in the 80s but what about today? Are ADAM files still useful? This presentation will show how the DBA can define and maintain ADAM files, and how the end-user can access them. It also will discuss read and write performance issues in an inefficiently tuned ADAM environment.

Newer versions of ADABAS support superdescriptors, which can contain more than 5 basic fields, making hyperdescriptors unnecessary for this approach. But hyperdescriptors may be used in many other cases, for example to translate fields or to store complimentary values. This presentation will show hyperexit examples (HEX1-31) and their useful inte-gration in applications.

Another little known and not often used ADABAS feature is coupling. Logical record types and relations can be integrated in one ADABAS file during the denormalization process. Access statistics, at a later time, can show many joins between entities and justify the use of coupling. If integration is not possible, ADABAS supports physical and soft coupling. This presentation will show the differences between logical, physical, and also soft coupling from a DBA as well as application programmer standpoint by using ADABAS utilities, ADABAS direct calls and NATURAL code.

With ADABAS version 5.3.2, Software AG introduced in July 1994 multi-client support. Records for multiple users or groups of users can be stored in a single ADABAS physical file defined as "multiclient." The multi-client feature divides the physical file into multiple logical files by attaching an internal owner ID to each record. This presentation will show how to define and load such a multi-client file.